u.s. forces then shot back. nato has not said whether it considers it an inside attack at this point. the number of troops killed since the u.s.-led invasion in 2001 is now exactly 2,000. >>> the first presidential debate of the campaign is in three days. today, both parties were trying to lower expectations, which is typical. what wasn't typical today is what anne romney had to say about her husband and her concerns if he becomes president. nbc bay area's kristin walker has the latest. >> reporter: with four mock debates under his bet, the president will rally supporters in nevada before jumping in to the debate preps ring with senator john kerry, his sparring partner, channelling mitt romney. in an iowa poll out today, president obama got another boost, leaving governor romney by four points, 49 to 45%. the president at ease, even making fun of his own gaffe. >> i want to see us export more jobs. export more products. excuse me. excuse me -- i was channelling my opponent there for a second. >> reporter: last w